1. Field of the Invention
The present invention relates to a fan and more specifically, to a fan preferably for use in a high humidity environment.
2. Description of the Related Art
JP-A 2000-152547 discloses a fan apparatus arranged to circulate air inside a refrigerator. The fan apparatus includes a motor frame, a stator, a bearing, a rotor, and a fan. A tubular portion arranged in a center of the motor frame is press fitted to the stator. The bearing is arranged inside the tubular portion. The stator is molded with a molding layer made of a synthetic resin except in an inner circumferential surface of a stator core. The rotor includes a rotating shaft, a cup-shaped rotor yoke, and a rotor magnet. The rotating shaft is inserted in the bearing. An upper portion of the rotating shaft is fixed to the rotor yoke. The rotor magnet is arranged on a cylindrical portion of the rotor yoke. The fan includes a base portion arranged to cover the rotor yoke, and blade portions arranged to project outward from the base portion. The fan apparatus is installed in a cooling compartment of the refrigerator with an opening of the rotor yoke facing obliquely downward.
In the case of a fan used in a high humidity environment, such as in a refrigerator or the like, a freezing or accumulation of water in a space between an impeller and a rotating portion of a motor may happen. This may lead to unbalanced rotation of the impeller during driving of the fan. Moreover, accumulation of frost in a space inside the impeller or the rotating portion may lead to a disturbance of the rotation of the impeller, i.e., a so-called impeller lock, because of a contact of the frost with a stationary portion.